Senin, 31 Agustus 2009

Fungsi Hard Disk

Manajemen Hard Disk di Linux - Partisi Hard Disk dengan Parted Print E-mail
Thursday, 27 April 2006
Mengatur partisi dengan baik adalah salah satu cara mengoptimalkan pemakaian hard disk. Menghapus, membuat, mengubah ukuran, dan memberi label partisi kini juga dapat Anda lakukan dalam sistem Linux. Semuanya dengan mengandalkan tool gratis dan open source!

Mengatur partisi dengan baik adalah salah satu cara mengoptimalkan pemakaian hard disk. Menghapus, membuat, mengubah ukuran, dan memberi label partisi kini juga dapat Anda lakukan dalam sistem Linux. Semuanya dengan mengandalkan tool gratis dan open source!

Image

Anda tentu tidak asing dengan istilah partisi maupun tabel partisi. Dua entitas inilah yang mendefinisikan ‘ruangan’ pada hard disk. Bagi Anda yang tergolong pengguna PC awam atau tidak terlalu paham mengenai partisi, suatu hard disk dapat dianalogikan seperti sebidang tanah kosong. Sebelum dapat dipakai, tanah tersebut harus dibagi dalam petak-petak kecil terlebih dahulu. Petak inilah yang diibaratkan seperti partisi. Adapun tabel partisi diandaikan papan keterangan di depan area tanah yang menjelaskan berapa petak yang di dalam area tanah dan berapa luas masing-masing petak. Di dalam petak ini nantinya “ditanami” data, yang dalam wujudnya sehari-hari dapat dilihat sebagai file.

Sebelum dapat ditanami, petak-petak tersebut harus diolah terlebih dahulu. Proses pengolahan inilah yang dikenal sebagai proses format hard disk. Saat melakukan format, Anda dapat memilih berbagai format sistem file (file system). Apabila di Windows, tersedia format FAT atau NTFS. Di Linux, dikenal beberapa sistem file, diantaranya yang cukup populer adalah sistem file ext2 dan ext3.

Sebelum mulai mengutak-atik partisi sistem Linux, sekilas akan dijelaskan bagaimana sistem Linux mendeteksi hard disk Anda. Hard disk biasanya diakses lewat perantaraan file dibawah direktori /dev dan namanya diawali dengan string hd. Lebih jelasnya, hard disk Anda akan dipetakan seperti daftar berikut ini.

Primary IDE master /dev/hda
Primary IDE slave /dev/hdb
Secondary IDE master /dev/hdc
Secondary IDE slave /dev/hdd

Untuk penomoran partisi, Linux menggunakan skema seperti berikut ini.
Partisi primary pertama sampai keempat
/dev/hd*1 - /dev/hd*4
Partisi logical pertama sampai keempat
/dev/hd*5 - /dev/hd*8


Tanda (*) merupakan pengganti huruf ‘a’ sampai dengan ‘z’, misalnya hda, hdb, hdc, dan seterusnya.

Pada praktek Linux kali ini akan digunakan tool berbasis command line bernama parted. Tool ini digunakan untuk mengelola partisi hard disk, dengan fungsi-fungsi antara lain seperti berikut ini.

  • Menambah dan menghapus partisi.
  • Mengubah ukuran partisi (memperbesar dan memperkecil).
  • Memberi label partisi.
  • Menggeser partisi.
  • Meng-copy isi partisi.

Pembahasan akan lebih ditekankan pada langkah nomor 1 hingga 3 dan langkah untuk menyelamatkan partisi hard disk yang terhapus.

Laptop


LAPTOP.Laptop is a very powerful tool in our laptops can listen to, typing, drawing, playing facebook friendster, blogger and played very practical game.Laptop be in play when the bus, car, train, plane anywhere in unless we back up the motorcycle, bajaj and bajaj bemo due in and the very noisy bemo we will be noise by sound-wheeler and bought a laptop bemo.saya worth seven million seratus.laptop which I bought brand can also compact.Laptop for photos-images if there is the camera if that does not mean that there could not kia foto.Jika photo-sometimes in the love of laptop bag for a laptop bag and there was not arbitrary in order not to collide security if we have a laptop should be treated so as not to damage and not to get wet because when exposed to water konslet it will be.

fungsi Processor

Penjelasan Tentang Processor

Nah, melanjutkan pembahasan sebelumnya, sekarang akan kita bahas mengenai komponen komputer yang penting banget yaitu PROCESSOR. Tak terasa sudah masuk bagian ke-5 pembahasan mengenai komponen komputer. Penjelasan kali ini mungkin akan sedikit panjang, dan akan disambung pada penjelasan berikutnya, karena membahas processor sama saja dengan membaca buku setebal 500 halaman. Namun saya akan menjelaskan secara simpel dan mudah dimengerti bagi orang awam, tentunya tidak terlalu mendetail penjelasan tentang processor ini.

Processor atau yang lebih dikenal dengan sebutan CPU (Central Processing Unit), merupakan bagian dari komputer yang berfungsi sebagai pusat untuk memproses segala sesuatu yang akan dilakukan oleh komputer. Boleh dikatakan bahwa processor merupakan otak dari sebuah komputer. Bayangkan saja jika manusia tidak memiliki otak, maka tentunya manusia tersebut tidak dapat berbuat apa-apa, dan bisa dikatakan sebagai mayat hidup (kaya zombie donk). Apapun aktivitas yang dilakukan oleh komputer, yang memprosesnya adalah processor.

Silahkan lihat gambar processor dibawah ini !

Merunut sejarah, processor telah banyak mengalami revolusi/perubahan, baik dari segi bentuk/arsitektur, fungsi dan juga kecepatan. Dari jaman processor keluaran Intel yaitu processor Intel 4004 (Generasi awal tapi bukan yang pertama) hingga saat ini yaitu Intel Core 2 Processor. Perbedaannya tentu sangat-sangat jauh baik dari segi bentuk, fungsi dan kecepatan. Intel 4004 memiliki clock speed sebesar 108KHz, jumlah transistor 2300, belum terdapat cache, bus speed 108 KHz, dan berfungsi untuk manipulasi aritmatika dasar. Processor Intel Core 2 Processor memiliki clock speed sebesar 3,2 GHz, jumlah transistor sebanyak 820 juta, cache sebesar 12 MB, bus speed 1600 MHz, dan memiliki fungsi yang sangat kompleks untuk multimedia, komputasi dan sebagainya (fungsi komputer saat ini).

Lihat gambar dibawah ini !

Intel 4004

Intel Core 2 Processor

Fungsi sebuah processor dalam komputer sangatlah penting, karena processor merupakan pusat untuk mengontrol dan memproses kerja sebuah komputer. Sebagai contoh fungsi dari processor adalah ketika Anda hendak menjalankan sebuah aplikasi seperti memutar lagu pada sebuah player seperti Winamp. Pertama-tama tentunya Anda akan mengklik icon Winamp untuk memainkan lagu yang Anda inginkan. Ketika Anda klik Winamp, mouse memberikan sinyal kepada komputer Anda melalui kabel mouse menuju mainboard Anda. Kemudian mainboard melalui jalur khusus, sinyal tersebut diteruskan melalui sebuah jalur BUS yang akan menuju ke Memori Utama, setelah diregister di memori utama, baru kemudian diteruskan menuju Processor untuk diolah sinyal yang dikirimkan tersebut. Setelah processor memproses sinyal tersebut (pengecekan request sinyal tersebut dapat dipenuhi atau tidak), processor akan mengirimkan sinyal kembali kepada komponen-komponen lainnya yang diperlukan untuk menjalankan program Winamp tersebut (seperti harddisk, memory dan sebagainya). Barulah program Winamp akan tampil di monitor Anda.

Perlu Anda ketahui, processor hanya dapat mengenali instruksi dengan notasi bilangan Biner (ex.01010001010). Merupakan notasi untuk perangkat elektronik dimana bilangan NOL (0) menandakan tidak terdapat sinyal listrik, dan bilangan SATU (1) menandakan adanya sinyal listrik. Tentunya urutan proses tersebut tidak dapat dibayangkan hanya sekejap mata saja, karena kecepatan processor yang dapat mencapai 3,2 GHz (3200 Juta getaran perdetik), jadi prosesnya sangat cepat hanya sepersekian mili detik saja.

Pada awalnya, processor hanya difungsikan untuk pengolahan aritmatika saja, seperti halnya kalkulator pada saat ini. Namun sekarang ini processor telah bergeser fungsinya mengarah ke multimedia.

BERSAMBUNG….

Senin, 24 Agustus 2009

My Handpone


Handpone.Pada on four two thousand eight handpane I got from my parents because on the fourth of two thousand eight birthday and I finally I got a nokia handpone although not too good but I should be grateful because it was purchased by handpone that money.Handpone communication tools practical for small and practical shape then almost everyone has handpone, because handpone also must have berinternet.Semua people unless handpone unable yag. therefore we should appreciate what has ada.Aku pleased handpone if I get bored I can listen to songs mantab-song and if I was tired of me playing on facebook handpone because the longer it will be more modern times such as electronic devices such as handpone, computers, laptops and other lain.handpone was a very sophisticated tool because we can see the weather on - date without seeing the calendar and we can use without wearing handpone can listrik.di handpone posed for pictures in his camera handpone there. Handpone there are several kinds such as handpone nokia, sony erecsen and much lagi.Itulah progress over time, although Indonesia not too sophisticated, but we have improved Indonesia
> swap


Senin, 10 Agustus 2009

Motherboard

Motherboard

From Wikipedia, the free encyclopedia

Jump to: navigation, search
Motherboard

The ASUS A8N VM CSM
Connects to Microprocessors via one of:
  • sockets
  • Slots (on older motherboards)

Main memory via one of:

  • Slots
  • Sockets for individual chips (on old motherboards)

Peripherals via one of:

Expansion cards via one of:

Form factors ATX
microATX
AT (on older motherboards)
Baby AT (on older motherboards)
Others
Common manufacturers ASUS
Foxconn
Intel
XFX
Others

A motherboard is the central printed circuit board (PCB) in some complex electronic systems, such as modern personal computers. The motherboard is sometimes alternatively known as the mainboard, system board, or, on Apple computers, the logic board.[1] It is also sometimes casually shortened to mobo.[2]

Contents

[hide]

[edit] History

Prior to the advent of the microprocessor, a computer was usually built in a card-cage case or mainframe with components connected by a backplane consisting of a set of slots themselves connected with wires; in very old designs the wires were discrete connections between card connector pins, but printed-circuit boards soon became the standard practice. The central processing unit, memory and peripherals were housed on individual printed circuit boards which plugged into the backplane.

During the late 1980s and 1990s, it became economical to move an increasing number of peripheral functions onto the motherboard (see below). In the late 1980s, motherboards began to include single ICs (called Super I/O chips) capable of supporting a set of low-speed peripherals: keyboard, mouse, floppy disk drive, serial ports, and parallel ports. As of the late 1990s, many personal computer motherboards supported a full range of audio, video, storage, and networking functions without the need for any expansion cards at all; higher-end systems for 3D gaming and computer graphics typically retained only the graphics card as a separate component.

The early pioneers of motherboard manufacturing were Micronics, Mylex, AMI, DTK, Hauppauge, Orchid Technology, Elitegroup, DFI, and a number of Taiwan-based manufacturers.

Popular personal computers such as the Apple II and IBM PC had published schematic diagrams and other documentation which permitted rapid reverse-engineering and third-party replacement motherboards. Usually intended for building new computers compatible with the exemplars, many motherboards offered additional performance or other features and were used to upgrade the manufacturer's original equipment.

The term mainboard is archaically applied to devices with a single board and no additional expansions or capability. In modern terms this would include embedded systems, and controlling boards in televisions, washing machines etc. A motherboard specifically refers to a printed circuit with the capability to add/extend its performance/capabilities with the addition of "daughterboards".

[edit] Overview

An Acer E360 motherboard made by Foxconn, from 2005, with a large number of integrated peripherals. This board's nForce3 chipset lacks a traditional northbridge.

Most computer motherboards produced today are designed for IBM-compatible computers, which currently account for around 90% of global PC sales[citation needed]. A motherboard, like a backplane, provides the electrical connections by which the other components of the system communicate, but unlike a backplane, it also hosts the central processing unit, and other subsystems and devices.

Motherboards are also used in many other electronics devices such as mobile phones, stop-watches, clocks, and other small electronic devices.

A typical desktop computer has its microprocessor, main memory, and other essential components on the motherboard. Other components such as external storage, controllers for video display and sound, and peripheral devices may be attached to the motherboard as plug-in cards or via cables, although in modern computers it is increasingly common to integrate some of these peripherals into the motherboard itself.

An important component of a motherboard is the microprocessor's supporting chipset, which provides the supporting interfaces between the CPU and the various buses and external components. This chipset determines, to an extent, the features and capabilities of the motherboard.

Modern motherboards include, at a minimum:

  • sockets (or slots) in which one or more microprocessors are installed[3]
  • slots into which the system's main memory is installed (typically in the form of DIMM modules containing DRAM chips)
  • a chipset which forms an interface between the CPU's front-side bus, main memory, and peripheral buses
  • non-volatile memory chips (usually Flash ROM in modern motherboards) containing the system's firmware or BIOS
  • a clock generator which produces the system clock signal to synchronize the various components
  • slots for expansion cards (these interface to the system via the buses supported by the chipset)
  • power connectors flickers, which receive electrical power from the computer power supply and distribute it to the CPU, chipset, main memory, and expansion cards.[4]
The Octek Jaguar V motherboard from 1993.[5] This board has 6 ISA slots but few onboard peripherals, as evidenced by the lack of external connectors.

Additionally, nearly all motherboards include logic and connectors to support commonly-used input devices, such as PS/2 connectors for a mouse and keyboard. Early personal computers such as the Apple II or IBM PC included only this minimal peripheral support on the motherboard. Occasionally video interface hardware was also integrated into the motherboard; for example on the Apple II, and rarely on IBM-compatible computers such as the IBM PC Jr. Additional peripherals such as disk controllers and serial ports were provided as expansion cards.

Given the high thermal design power of high-speed computer CPUs and components, modern motherboards nearly always include heat sinks and mounting points for fans to dissipate excess heat.

[edit] CPU sockets

A CPU socket or CPU slot is an electrical component that attaches to a printed circuit board (PCB) and is designed to house a CPU (also called a microprocessor). It is a special type of integrated circuit socket designed for very high pin counts. A CPU socket provides many functions, including providing a physical structure to support the CPU, providing support for a heat sink, facilitating replacement (as well as reducing cost) and most importantly forming an electrical interface both with the CPU and the PCB. CPU sockets can most often be found in most desktop and server computers (laptops typically use surface mount CPUs), particularly those based on the Intel x86 architecture on the motherboard.

[edit] Integrated peripherals

Block diagram of a modern motherboard, which supports many on-board peripheral functions as well as several expansion slots.

With the steadily declining costs and size of integrated circuits, it is now possible to include support for many peripherals on the motherboard. By combining many functions on one PCB, the physical size and total cost of the system may be reduced; highly-integrated motherboards are thus especially popular in small form factor and budget computers.

For example, the ECS RS485M-M,[6] a typical modern budget motherboard for computers based on AMD processors, has on-board support for a very large range of peripherals:

Expansion cards to support all of these functions would have cost hundreds of dollars even a decade ago, however as of April 2007 such highly-integrated motherboards are available for as little as $30 in the USA.

[edit] Peripheral card slots

A typical motherboard of 2009 will have a different number of connections depending on its standard. A standard ATX motherboard will typically have 1x PCI-E 16x connection for a graphics card, 2x PCI slots for various expansion cards and 1x PCI-E 1x which will eventually supersede PCI.

A standard Super ATX motherboard will have 1x PCI-E 16x connection for a graphics card. It will also have a varying number of PCI and PCI-E 1x slots. It can sometimes also have a PCI-E 4x slot. This varies between brands and models.

Some motherboards have 2x PCI-E 16x slots, to allow more than 2 monitors without special hardware or to allow use of a special graphics technology called SLI (for Nvidia) and Crossfire (for ATI). These allow 2 graphics cards to be linked together, to allow better performance in intensive graphical computing tasks, such as gaming and video-editing.

As of 2007, virtually all motherboards come with at least 4x USB ports on the rear, with at least 2 connections on the board internally for wiring additional front ports that are built into the computer's case. Ethernet is also included now. This is a standard networking cable for connecting the computer to a network or a modem. A sound chip is always included on the motherboard, to allow sound to be output without the need for any extra components. This allows computers to be far more multimedia-based than before. Cheaper machines now often have their graphics chip built into the motherboard rather than a separate card.

[edit] Temperature and reliability

Motherboards are generally air cooled with heat sinks often mounted on larger chips, such as the northbridge, in modern motherboards. If the motherboard is not cooled properly, it can cause the computer to crash. Passive cooling, or a single fan mounted on the power supply, was sufficient for many desktop computer CPUs until the late 1990s; since then, most have required CPU fans mounted on their heat sinks, due to rising clock speeds and power consumption. Most motherboards have connectors for additional case fans as well. Newer motherboards have integrated temperature sensors to detect motherboard and CPU temperatures, and controllable fan connectors which the BIOS or operating system can use to regulate fan speed. Some higher-powered computers (which typically have high-performance processors and large amounts of RAM, as well as high-performance video cards) use a water-cooling system instead of many fans.

Some small form factor computers and home theater PCs designed for quiet and energy-efficient operation boast fan-less designs. This typically requires the use of a low-power CPU, as well as careful layout of the motherboard and other components to allow for heat sink placement.

A 2003 study[7] found that some spurious computer crashes and general reliability issues, ranging from screen image distortions to I/O read/write errors, can be attributed not to software or peripheral hardware but to aging capacitors on PC motherboards. Ultimately this was shown to be the result of a faulty electrolyte formulation.[8]

For more information on premature capacitor failure on PC motherboards, see capacitor plague.

Motherboards use electrolytic capacitors to filter the DC power distributed around the board. These capacitors age at a temperature-dependent rate, as their water based electrolytes slowly evaporate. This can lead to loss of capacitance and subsequent motherboard malfunctions due to voltage instabilities. While most capacitors are rated for 2000 hours of operation at 105 °C,[9] their expected design life roughly doubles for every 10 °C below this. At 45 °C a lifetime of 15 years can be expected. This appears reasonable for a computer motherboard, however many manufacturers have delivered substandard capacitors,[citation needed] which significantly reduce life expectancy. Inadequate case cooling and elevated temperatures easily exacerbate this problem. It is possible, but tedious and time-consuming, to find and replace failed capacitors on PC motherboards; it is less expensive to buy a new motherboard than to pay for such a repair.[citation needed]

[edit] Form factor

microATX form factor motherboard

Motherboards are produced in a variety of sizes and shapes ("form factors"), some of which are specific to individual computer manufacturers. However, the motherboards used in IBM-compatible commodity computers have been standardized to fit various case sizes. As of 2007, most desktop computer motherboards use one of these standard form factors—even those found in Macintosh and Sun computers which have not traditionally been built from commodity components.

Laptop computers generally use highly integrated, miniaturized, and customized motherboards. This is one of the reasons that laptop computers are difficult to upgrade and expensive to repair. Often the failure of one laptop component requires the replacement of the entire motherboard, which is usually more expensive than a desktop motherboard due to the large number of integrated components.

[edit] Nvidia SLI and ATI Crossfire

Nvidia SLI and ATI Crossfire technology allows two or more of the same series graphics cards to be linked together to allow faster graphics-processing capabilities. Almost all medium- to high-end Nvidia cards and most high-end ATI cards support the technology.

They both require compatible motherboards. There is an obvious need for 2x PCI-E 16x slots to allow two cards to be inserted into the computer. The same function can be achieved in 650i motherboards by NVIDIA, with a pair of x8 slots. Originally, tri-Crossfire was achieved at 8x speeds with two 16x slots and one 8x slot; albeit at a slower speed. ATI opened the technology up to Intel in 2006, and all new Intel chipsets now support Crossfire.

SLI is a little more proprietary in its needs. It requires a motherboard with Nvidia's own NForce chipset series to allow it to run (exception: select Intel X58 chipset based motherboards).

It is important to note that SLI and Crossfire will not usually scale to 2x the performance of a single card when using a dual setup. They also do not double the effective amount of VRAM or memory bandwidth.

[edit] Bootstrapping using the BIOS

Motherboards contain some non-volatile memory to initialize the system and load an operating system from some external peripheral device. Microcomputers such as the Apple II and IBM PC used read-only memory chips, mounted in sockets on the motherboard. At power-up, the central processor would load its program counter with the address of the boot ROM, and start executing ROM instructions, displaying system information on the screen and running memory checks, which would in turn start loading memory from an external or peripheral device (disk drive). If none is available, then the computer can perform tasks from other memory stores or display an error message, depending on the model and design of the computer and version of the BIOS.

Most modern motherboard designs use a BIOS, stored in an EEPROM chip soldered to the motherboard, to bootstrap the motherboard. (Socketed BIOS chips are widely used, also.) By booting the motherboard, the memory, circuitry, and peripherals are tested and configured. This process is known as a computer Power-On Self Test (POST) and may include testing some of the following devices:

Monitor

Monitor

Monitor adalah suatu tipe data abstrak yang dapat mengatur aktivitas serta penggunaan resource oleh beberapa thread. Ide monitor pertama kali diperkenalkan oleh C.A.R Hoare dan Per Brinch-Hansen pada awal 1970-an.

Monitor terdiri atas data-data private dengan fungsi-fungsi public yang dapat mengakses data-data tersebut. Method-method dalam suatu monitor sudah dirancang sedemikian rupa agar hanya ada satu buah method yang dapat bekerja pada suatu saat. Hal ini bertujuan untuk menjaga agar semua operasi dalam monitor bersifat mutual exclusion.

Monitor dapat dianalogikan sebagai sebuah bangunan dengan tiga buah ruangan yaitu satu buah ruangan kontrol, satu buah ruang-tunggu-masuk, satu buah ruang-tunggu-dalam. Ketika suatu thread memasuki monitor, ia memasuki ruang-tunggu-masuk (enter). Ketika gilirannya tiba, thread memasuki ruang kontrol (acquire), di sini thread menyelesaikan tugasnya dengan shared resource yang berada di ruang kontrol (owning). Jika tugas thread tersebut belum selesai tetapi alokasi waktu untuknya sudah habis atau thread tersebut menunggu pekerjaan thread lain selesai, thread melepaskan kendali atas monitor (release) dan dipindahkan ke ruang-tunggu-dalam (waiting queue). Ketika gilirannya tiba kembali, thread memasuki ruang kontrol lagi (acquire). Jika tugasnya selesai, ia keluar dari monitor (release and exit).

Gambar 20.1. Monitor

Monitor

Karena masalah sinkronisasi begitu rumit dan beragam, monitor menyediakan tipe data condition untuk programmer yang ingin menerapkan sinkronisasi yang sesuai untuk masalah yang dihadapinya. Condition memiliki operasi-operasi:

  1. Wait, sesuai namanya thread yang memanggil fungsi ini akan dihentikan kerjanya.

  2. Signal, jika suatu thread memanggil fungsi ini, satu (dari beberapa) thread yang sedang menunggu akan dibangunkan untuk bekerja kembali. Operasi ini hanya membangunkan tepat satu buah thread yang sedang menunggu. Jika tidak ada thread yang sedang menunggu, tidak akan terjadi apa-apa (bedakan dengan operasi buka pada semafor).

Ilustrasi monitor dengan condition variable:

Gambar 20.2. Monitor dengan condition variable

Monitor dengan condition variable

Bayangkan jika pada suatu saat sebuah thread A memanggil fungsi signal pada condition x (x.signal()) dan ada sebuah thread B yang sedang menunggu operasi tersebut (B telah memanggil fungsi x.wait() sebelumnya), ada dua kemungkinan keadaan thread A dan B setelah A mengeksekusi x.signal():

  1. Signal-and-Wait, A menunggu sampai B keluar dari monitor atau menunggu condition lain yang dapat mengaktifkannya.

  2. Signal-and-Continue, B menunggu sampai A keluar dari monitor atau menunggu condition lain yang dapat mengakifkannya.

Monitor dikembangkan karena penggunaan semafor yang kurang praktis. Hal itu disebabkan kesalahan pada penggunaan semafor tidak dapat dideteksi oleh compiler. Keuntungan memakai monitor:

  1. Kompilator pada bahasa pemrograman yang telah mengimplementasikan monitor akan memastikan bahwa resource yang dapat diakses oleh beberapa thread dilindungi oleh monitor, sehingga prinsip mutual exclusion tetap terjaga.

  2. Kompilator bisa memeriksa kemungkinan adanya deadlock.

Memory card

Memory card

From Wikipedia, the free encyclopedia

Jump to: navigation, search

A memory card or flash memory card is a solid-state electronic flash memory data storage device capable of storing digital contents. These are mainly used with digital cameras, handheld and Mobile computers, mobile phones, music players, digital cinematography cameras, video game consoles, and other electronics. They offer high re-record-ability, power-free storage, small form factor, and rugged environmental specifications. There are also non-solid-state memory cards that do not use flash memory, and there are different types of flash memory.

There are many different types of memory cards and jobs they are used for. Some common places include in digital cameras, game consoles, cell phones, and industrial applications. PC card (PCMCIA) were among first commercial memory card formats (type I cards) to come out in the 1990s, but are now only mainly used in industrial applications and for I/O jobs (using types I/II/III), as a connection standard for devices (such as a modem). Also in 1990s, a number of memory card formats smaller than PC Card came out, including CompactFlash, SmartMedia, and Miniature Card. In other areas, tiny embedded memory cards (SID) were used in cell phones, game ds. The desire for ultra-small cards for cell-phones, PDAs, and compact digital cameras drove a trend toward smaller cards that left the previous generation of "compact" cards looking big. In digital cameras SmartMedia and CompactFlash had been very successful, in 2001 SM alone captured 50% of the digital camera market and CF had a strangle hold on professional digital cameras. By 2005 however, SD/MMC had nearly taken over SmartMedia's spot, though not to the same level and with stiff competition coming from Memory Stick variants, xD, as well as CompactFlash. In industrial fields, even the venerable PC card (PCMCIA) memory cards still manage to maintain a niche, while in cell-phones and PDAs, the memory card market is highly fragmented.

Nowadays, most new PCs have built-in slots for a variety of memory cards; Memory Stick, CompactFlash, SD, etc. Some digital gadgets support more than one memory card to ensure compatibility.

Contents

[hide]

[edit] Data table of selected memory card formats

Name Acronym Form factor DRM
PC Card PCMCIA 85.6 × 54 × 3.3 mm None
CompactFlash I CF-I 43 × 36 × 3.3 mm None
CompactFlash II CF-II 43 × 36 × 5.5 mm None
SmartMedia SM / SMC 45 × 37 × 0.76 mm None
Memory Stick MS 50.0 × 21.5 × 2.8 mm MagicGate
Memory Stick Duo MSD 31.0 × 20.0 × 1.6 mm MagicGate
Memory Stick PRO Duo MSPD 31.0 × 20.0 × 1.6 mm MagicGate
Memory Stick PRO-HG Duo MSPDX 31.0 × 20.0 × 1.6 mm MagicGate
Memory Stick Micro M2 M2 15.0 × 12.5 × 1.2 mm MagicGate
Miniature Card
37 x 45 x 3.5 mm None
Multimedia Card MMC 32 × 24 × 1.5 mm None
Reduced Size Multimedia Card RS-MMC 16 × 24 × 1.5 mm None
MMCmicro Card MMCmicro 12 × 14 × 1.1 mm None
Secure Digital card SD 32 × 24 × 2.1 mm CPRM
SxS SxS

Universal Flash Storage UFS

miniSD card miniSD 21.5 × 20 × 1.4 mm CPRM
microSD card microSD 11 × 15 × 0.7 mm CPRM
xD-Picture Card xD 20 × 25 × 1.7 mm None
Intelligent Stick iStick 24 x 18 x 2.8 mm None
Serial Flash Module SFM 45 x 15 mm None
µ card µcard 32 x 24 x 1 mm Unknown
NT Card NT NT+ 44 x 24 x 2.5 mm None

Since many EEPROM devices only allow a limited number of write cycles, some of these cards incorporate wear levelling algorithms to spread the wear and to avoid wearing out specific places which are often written to.

[edit] Overview of all memory card types

Miniaturization is evident in memory card creation; over time, the physical sizes of the memory cards grow smaller while their respective logical sizes grow larger. The memory cards listed from left to right are: Compact flash (32 MB), SD (128 MB), miniSD (1.0 GB), and microSD (2.0 GB).
  • PCMCIA ATA Type I Flash Memory Card (PC Card ATA Type I) (max 8 GB (8 GiB) flash as of 2005)
    • PCMCIA Linear Flash Cards, SRAM cards, etc.
    • PCMCIA Type II, Type III cards
  • CompactFlash Card (Type I), CompactFlash High-Speed (max 32 GB as of 2008)
  • CompactFlash Type II, CF+(CF2.0), CF3.0
    • Microdrive (max 6 GB as of 2005)
  • MiniCard (Miniature Card) (max 64 MB (64 MiB))
  • SmartMedia Card (SSFDC) (max 128 MB) (3.3 V,5 V)
  • xD-Picture Card, xD-Picture Card Type M
  • Memory Stick, MagicGate Memory Stick (max 128 MB); Memory Stick Select, MagicGate Memory Stick Select ("Select" means: 2x128 MB with A/B switch)
  • SecureMMC
  • Secure Digital (SD Card), Secure Digital High-Speed, Secure Digital Plus/Xtra/etc (SD with USB connector)
    • miniSD Card
    • microSD Card (aka Transflash, T-Flash)
    • SDHC
  • MU-Flash (Mu-Card) (Mu-Card Alliance of OMIA)
  • C-Flash
  • SIM card (Subscriber Identity Module)
  • Smart card (ISO 7810 Card Standard , ISO 7816 Card Standard, etc.)
  • UFC (USB FlashCard) [1] (uses USB)
  • FISH Universal Transportable Memory Card Standard (uses USB)
  • Disk memory cards:
  • Intelligent Stick (iStick, a USB-based flash memory card with MMS)
  • SxS (S-by-S) memory card, a new memory card specification developed by Sandisk and Sony. SxS complies to the ExpressCard industry standard. [2]
  • Nexflash Winbond Serial Flash Moduel (SFM) cards, size range 1 mb, 2 mb and 4 mb.

[edit] Memory cards in video game consoles

Many video game consoles have used proprietary solid-state memory cards to store data. In recent years read-only optical discs have replaced these memory cards in most current home console systems. However most portable gaming systems still rely on custom memory cartridges, due to their low power consumption, smaller physical size and reduced mechanical complexity.

The sizes in parenthesis are those of the official, first-party memory cards.

Microphone

Microphone

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A microphone, sometimes colloquially called a mic or mike (both pronounced /ˈmaɪk/), is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. Microphones are used in many applications such as telephones, tape recorders, hearing aids, motion picture production, live and recorded audio engineering, in radio and television broadcasting and in computers for recording voice, VoIP, and for non-acoustic purposes such as ultrasonic checking.

A Neumann U87 condenser microphone

The most common design today uses a thin membrane which vibrates in response to sound pressure. This movement is subsequently translated into an electrical signal. Most microphones in use today for audio use electromagnetic induction (dynamic microphone), capacitance change (condenser microphone, pictured right), piezoelectric generation, or light modulation to produce the signal from mechanical vibration.

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[edit] Varieties

The sensitive transducer element of a microphone is called its element or capsule. A complete microphone also includes a housing, some means of bringing the signal from the element to other equipment, and often an electronic circuit to adapt the output of the capsule to the equipment being driven. Microphones are referred to by their transducer principle, such as condenser, dynamic, etc., and by their directional characteristics. Sometimes other characteristics such as diaphragm size, intended use or orientation of the principal sound input to the principal axis (end- or side-address) of the microphone are used to describe the microphone.

[edit] Condenser, capacitor or electrostatic microphone

Inside the Oktava 319 condenser microphone

In a condenser microphone, also known as a capacitor or electrostatic microphone, the diaphragm acts as one plate of a capacitor, and the vibrations produce changes in the distance between the plates. There are two methods of extracting an audio output from the transducer thus formed: DC-biased and radio frequency (RF) or high frequency (HF) condenser microphones. With a DC-biased microphone, the plates are biased with a fixed charge (Q). The voltage maintained across the capacitor plates changes with the vibrations in the air, according to the capacitance equation (C = Q / V), where Q = charge in coulombs, C = capacitance in farads and V = potential difference in volts. The capacitance of the plates is inversely proportional to the distance between them for a parallel-plate capacitor. (See capacitance for details.) The assembly of fixed and movable plates is called an "element" or "capsule."

A nearly constant charge is maintained on the capacitor. As the capacitance changes, the charge across the capacitor does change very slightly, but at audible frequencies it is sensibly constant. The capacitance of the capsule (around 5–100 pF) and the value of the bias resistor (100 megohms to tens of gigohms) form a filter which is highpass for the audio signal, and lowpass for the bias voltage. Note that the time constant of an RC circuit equals the product of the resistance and capacitance.

Within the time-frame of the capacitance change (as much as 50 ms at 20 Hz audio signal), the charge is practically constant and the voltage across the capacitor changes instantaneously to reflect the change in capacitance. The voltage across the capacitor varies above and below the bias voltage. The voltage difference between the bias and the capacitor is seen across the series resistor. The voltage across the resistor is amplified for performance or recording.

AKG C451B small-diaphragm condenser microphone

RF condenser microphones use a comparatively low RF voltage, generated by a low-noise oscillator. The oscillator may either be frequency modulated by the capacitance changes produced by the sound waves moving the capsule diaphragm, or the capsule may be part of a resonant circuit that modulates the amplitude of the fixed-frequency oscillator signal. Demodulation yields a low-noise audio frequency signal with a very low source impedance. This technique permits the use of a diaphragm with looser tension, which may be used to achieve wider frequency response due to higher compliance. The RF biasing process results in a lower electrical impedance capsule, a useful byproduct of which is that RF condenser microphones can be operated in damp weather conditions which could create problems in DC-biased microphones whose insulating surfaces have become contaminated. The Sennheiser "MKH" series of microphones use the RF biasing technique.

Condenser microphones span the range from telephone transmitters to inexpensive karaoke microphones to high-fidelity recording microphones. They generally produce a high-quality audio signal and are now the popular choice in laboratory and studio recording applications. The inherent suitability of this technology is due to the very small mass that must be moved by the incident sound wave, unlike other microphone types which require the sound wave to do more work. They require a power source, provided either from microphone inputs as phantom power or from a small battery. Power is necessary for establishing the capacitor plate voltage, and is also needed to power the microphone electronics (impedance conversion in the case of electret and DC-polarized microphones, demodulation or detection in the case of RF/HF microphones). Condenser microphones are also available with two diaphragms, the signals from which can be electrically connected such as to provide a range of polar patterns (see below), such as cardioid, omnidirectional and figure-eight. It is also possible to vary the pattern smoothly with some microphones, for example the Røde NT2000 or CAD M179.

[edit] Electret condenser microphone

First patent on foil electret microphone by G. M. Sessler et al. (pages 1 to 3)

An electret microphone is a relatively new type of capacitor microphone invented at Bell laboratories in 1962 by Gerhard Sessler and Jim West.[1] The externally-applied charge described above under condenser microphones is replaced by a permanent charge in an electret material. An electret is a ferroelectric material that has been permanently electrically charged or polarized. The name comes from electrostatic and magnet; a static charge is embedded in an electret by alignment of the static charges in the material, much the way a magnet is made by aligning the magnetic domains in a piece of iron.

Due to their good performance and ease of manufacture, hence low cost, the vast majority of microphones made today are electret microphones; a semiconductor manufacturer[2] estimates annual production at over one billion units. Nearly all cell-phone, computer, PDA and headset microphones are electret types. They are used in many applications, from high-quality recording and lavalier use to built-in microphones in small sound recording devices and telephones. Though electret microphones were once considered low quality, the best ones can now rival traditional condenser microphones in every respect and can even offer the long-term stability and ultra-flat response needed for a measurement microphone. Unlike other capacitor microphones, they require no polarizing voltage, but often contain an integrated preamplifier which does require power (often incorrectly called polarizing power or bias). This preamp is frequently phantom powered in sound reinforcement and studio applications. Microphones designed for Personal Computer (PC) use, sometimes called multimedia microphones, use a stereo 3.5 mm plug (though a mono source) with the ring receiving power via a resistor from (normally) a 5 V supply in the computer; unfortunately, a number of incompatible dynamic microphones are fitted with 3.5 mm plugs too. While few electret microphones rival the best DC-polarized units in terms of noise level, this is not due to any inherent limitation of the electret. Rather, mass production techniques needed to produce microphones cheaply don't lend themselves to the precision needed to produce the highest quality microphones, due to the tight tolerances required in internal dimensions. These tolerances are the same for all condenser microphones, whether the DC, RF or electret technology is used.

[edit] Dynamic microphone

Patti Smith singing into a Shure SM58 (dynamic cardioid type) microphone

Dynamic microphones work via electromagnetic induction. They are robust, relatively inexpensive and resistant to moisture. This, coupled with their potentially high gain before feedback makes them ideal for on-stage use.

Moving-coil microphones use the same dynamic principle as in a loudspeaker, only reversed. A small movable induction coil, positioned in the magnetic field of a permanent magnet, is attached to the diaphragm. When sound enters through the windscreen of the microphone, the sound wave moves the diaphragm. When the diaphragm vibrates, the coil moves in the magnetic field, producing a varying current in the coil through electromagnetic induction. A single dynamic membrane will not respond linearly to all audio frequencies. Some microphones for this reason utilize multiple membranes for the different parts of the audio spectrum and then combine the resulting signals. Combining the multiple signals correctly is difficult and designs that do this are rare and tend to be expensive. There are on the other hand several designs that are more specifically aimed towards isolated parts of the audio spectrum. The AKG D 112, for example, is designed for bass response rather than treble[3]. In audio engineering several kinds of microphones are often used at the same time to get the best result.

Edmund Lowe using a ribbon microphone

Ribbon microphones use a thin, usually corrugated metal ribbon suspended in a magnetic field. The ribbon is electrically connected to the microphone's output, and its vibration within the magnetic field generates the electrical signal. Ribbon microphones are similar to moving coil microphones in the sense that both produce sound by means of magnetic induction. Basic ribbon microphones detect sound in a bidirectional (also called figure-eight) pattern because the ribbon, which is open to sound both front and back, responds to the pressure gradient rather than the sound pressure. Though the symmetrical front and rear pickup can be a nuisance in normal stereo recording, the high side rejection can be used to advantage by positioning a ribbon microphone horizontally, for example above cymbals, so that the rear lobe picks up only sound from the cymbals. Crossed figure 8, or Blumlein pair, stereo recording is gaining in popularity, and the figure 8 response of a ribbon microphone is ideal for that application.

Other directional patterns are produced by enclosing one side of the ribbon in an acoustic trap or baffle, allowing sound to reach only one side. The classic RCA Type 77-DX microphone has several externally-adjustable positions of the internal baffle, allowing the selection of several response patterns ranging from "Figure-8" to "Unidirectional". Such older ribbon microphones, some of which still give very high quality sound reproduction, were once valued for this reason, but a good low-frequency response could only be obtained if the ribbon was suspended very loosely, and this made them fragile. Modern ribbon materials, including new nanomaterials[4] have now been introduced that eliminate those concerns, and even improve the effective dynamic range of ribbon microphones at low frequencies. Protective wind screens can reduce the danger of damaging a vintage ribbon, and also reduce plosive artifacts in the recording. Properly designed wind screens produce negligible treble attenuation. In common with other classes of dynamic microphone, ribbon microphones don't require phantom power; in fact, this voltage can damage some older ribbon microphones. Some new modern ribbon microphone designs incorporate a preamplifier and, therefore, do require phantom power, and circuits of modern passive ribbon microphones, i.e., those without the aforementioned preamplifier, are specifically designed to resist damage to the ribbon and transformer by phantom power. Also there are new ribbon materials available that are immune to wind blasts and phantom power.

[edit] Carbon microphone

A carbon microphone, formerly used in telephone handsets, is a capsule containing carbon granules pressed between two metal plates. A voltage is applied across the metal plates, causing a small current to flow through the carbon. One of the plates, the diaphragm, vibrates in sympathy with incident sound waves, applying a varying pressure to the carbon. The changing pressure deforms the granules, causing the contact area between each pair of adjacent granules to change, and this causes the electrical resistance of the mass of granules to change. The changes in resistance cause a corresponding change in the voltage across the two plates, and hence in the current flowing through the microphone, producing the electrical signal. Carbon microphones were once commonly used in telephones; they have extremely low-quality sound reproduction and a very limited frequency response range, but are very robust devices.

Unlike other microphone types, the carbon microphone can also be used as a type of amplifier, using a small amount of sound energy to produce a larger amount of electrical energy. Carbon microphones found use as early telephone repeaters, making long distance phone calls possible in the era before vacuum tubes. These repeaters worked by mechanically coupling a magnetic telephone receiver to a carbon microphone: the faint signal from the receiver was transferred to the microphone, with a resulting stronger electrical signal to send down the line. (One illustration of this amplifier effect was the oscillation caused by feedback, resulting in an audible squeal from the old "candlestick" telephone if its earphone was placed near the carbon microphone.

[edit] Piezoelectric microphone

A crystal microphone uses the phenomenon of piezoelectricity — the ability of some materials to produce a voltage when subjected to pressure — to convert vibrations into an electrical signal. An example of this is Rochelle salt (potassium sodium tartrate), which is a piezoelectric crystal that works as a transducer, both as a microphone and as a slimline loudspeaker component. Crystal microphones were once commonly supplied with vacuum tube (valve) equipment, such as domestic tape recorders. Their high output impedance matched the high input impedance (typically about 10 megohms) of the vacuum tube input stage well. They were difficult to match to early transistor equipment, and were quickly supplanted by dynamic microphones for a time, and later small electret condenser devices. The high impedance of the crystal microphone made it very susceptible to handling noise, both from the microphone itself and from the connecting cable.

Piezoelectric transducers are often used as contact microphones to amplify sound from acoustic musical instruments, to sense drum hits, for triggering electronic samples, and to record sound in challenging environments, such as underwater under high pressure. Saddle-mounted pickups on acoustic guitars are generally piezoelectric devices that contact the strings passing over the saddle. This type of microphone is different from magnetic coil pickups commonly visible on typical electric guitars, which use magnetic induction, rather than mechanical coupling, to pick up vibration.

[edit] Fiber optical microphone

The fiber optical microphone is an entirely new microphone concept, first invented in Israel in 1984 by Drs. Alexander Paritsky and Alexander Kots.[5] Conversion of acoustical waves into electrical signals is achieved not by sensing changes in capacitance or magnetic fields (as with conventional microphones), but instead by sensing changes in light intensity. During operation, light from a laser source travels through an optical fiber to illuminate the surface of a tiny, sound-sensitive reflective diaphragm. Sound causes the diaphragm to vibrate, thereby minutely changing the intensity of the light it reflects. The modulated light is then transmitted over a second optical fiber to a photo detector, which transforms the intensity-modulated light into electrical signals for audio transmission or recording.

Typical fiber optical microphone (Optoacoustics' Optimic 1190)

The fiber optical microphone has very specific advantages over conventional microphones. First, no electronic or metal components are used in the microphone head or the connecting fibers, so the microphone does not react to or influence any electrical, magnetic, electrostatic or radioactive fields (this is called EMI/RFI immunity). The fiber optical microphone is therefore ideal for use in areas where conventional microphones are ineffective or dangerous, such as inside industrial turbines or in magnetic resonance imaging (MRI) equipment environments. Another advantage is the physical nature of optical fiber light propagation. The distance between the microphone's light source and its photo detector may be up to several kilometers without need for any preamplifier and/or other electrical device. Finally, fiber optical microphones possess high dynamic and frequency range, similar to the best high fidelity conventional microphones. They are robust, resistant to environmental changes in heat and moisture, and are excellent for noise-canceling applications.

Fiber optical microphones can be produced for any directionality or impedance matching. They have proven especially useful in medical applications (with particular success in MRI patient-to-staff communications), audio calibration and measurement, industrial equipment sensing, high-fidelity recording and law enforcement. A comprehensive range of commercial fiber optical microphones is manufactured by Optoacoustics, Ltd.[6]

[edit] Laser microphone

Laser microphones are often portrayed in movies as spy gadgets. A laser beam is aimed at the surface of a window or other plane surface that is affected by sound. The slight vibrations of this surface displace the returned beam, causing it to trace the sound wave. The vibrating laser spot is then converted back to sound. In a more robust and expensive implementation, the returned light is split and fed to an interferometer, which detects frequency changes due to the Doppler effect. The former implementation is a tabletop experiment; the latter requires an extremely stable laser and precise optics.

[edit] Liquid microphone

Early microphones did not produce intelligible speech, until Alexander Graham Bell made improvements including a variable resistance microphone/transmitter. Bell's liquid transmitter consisted of a metal cup filled with water with a small amount of sulfuric acid added. A sound wave caused the diaphragm to move, forcing a needle to move up and down in the water. The electrical resistance between the wire and the cup was then inversely proportional to the size of the water meniscus around the submerged needle. Elisha Gray filed a caveat for a version using a brass rod instead of the needle. Other minor variations and improvements were made to the liquid microphone by Majoranna, Chambers, Vanni, Sykes, and Elisha Gray, and one version was patented by Reginald Fessenden in 1903. These were the first working microphones, but they were not practical for commercial application. The famous first phone conversation between Bell and Watson took place using a liquid microphone.

[edit] MEMS microphone

The MEMS (MicroElectrical-Mechanical System) microphone is also called a microphone chip or silicon microphone. The pressure-sensitive diaphragm is etched directly into a silicon chip by MEMS techniques, and is usually accompanied with integrated preamplifier. Most MEMS microphones are variants of the condenser microphone design. Often MEMS microphones have built in analog-to-digital converter (ADC) circuits on the same CMOS chip making the chip a digital microphone and so more readily integrated with modern digital products. Major manufacturers producing MEMS silicon microphones are Wolfson Microelectronics (WM7xxx), Analog Devices, Akustica (AKU200x), Infineon (SMM310 product), Knowles Electronics, Memstech (MSMx) and Sonion MEMS.

[edit] Speakers as microphones

A loudspeaker, a transducer that turns an electrical signal into sound waves, is the functional opposite of a microphone. Since a conventional speaker is constructed much like a dynamic microphone (with a diaphragm, coil and magnet), speakers can actually work "in reverse" as microphones. The result, though, is a microphone with poor quality, limited frequency response (particularly at the high end), and poor sensitivity. In practical use, speakers are sometimes used as microphones in such applications as intercoms or walkie-talkies, where high quality and sensitivity are not needed.

However, there is at least one other practical application of this principle: Using a medium-size woofer placed closely in front of a "kick" (bass drum) in a drum set to act as a microphone. The use of relatively large speakers to transduce low frequency sound sources, especially in music production, is becoming fairly common. Since a relatively massive membrane is unable to transduce high frequencies, placing a speaker in front of a kick drum is often ideal for reducing cymbal and snare bleed into the kick drum sound. Less commonly, microphones themselves can be used as speakers, almost always as tweeters. This is less common, since microphones are not designed to handle the power that speaker components are routinely required to cope with. One instance of such an application was the STC microphone-derived 4001 super-tweeter, which was successfully used in a number of high quality loudspeaker systems from the late 1960s to the mid-70s. A well-known example of this use was the Bowers & Wilkins DM2a model.

[edit] Capsule design and directivity

The inner elements of a microphone are the primary source of differences in directivity. A pressure microphone uses a diaphragm between a fixed internal volume of air and the environment, and responds uniformly to pressure from all directions, so it is said to be omnidirectional. A pressure-gradient microphone uses a diaphragm which is at least partially open on both sides; the pressure difference between the two sides produces its directional characteristics. Other elements such as the external shape of the microphone and external devices such as interference tubes can also alter a microphone's directional response. A pure pressure-gradient microphone is equally sensitive to sounds arriving from front or back, but insensitive to sounds arriving from the side because sound arriving at the front and back at the same time creates no gradient between the two. The characteristic directional pattern of a pure pressure-gradient microphone is like a figure-8. Other polar patterns are derived by creating a capsule that combines these two effects in different ways. The cardioid, for instance, features a partially closed backside, so its response is a combination of pressure and pressure-gradient characteristics.[7]